84 resultados para Coastal basins


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For meroplanktonic larvae that must settle in coastal areas, their successful return to the shore is determined largely by physical transport processes; however, many organisms perform vertical movements to aid successful recruitment. In this study, daytime tidal vertical migration of megalopae of the velvet swimming crab Necora puber was investigated across two different exposures in the shallow waters of Plymouth Sound. Crabs were collected using a plankton net at the surface and near the bottom during flood and ebb tides. Distribution of the pelagic postlarvae was patchy and the abundance varied spatially in tens and thousands of metres. In temporal scales, the annual pattern was dominated by low occurrence of megalopae, punctuated by episodic peaks of high abundance. Most megalopae were collected at the surface irrespective of the tidal phase. The effect of wave exposure on the vertical migration of megalopae was not clear, although there was a general higher abundance of megalopae on exposed shores. Daytime abundance in the water column appears to be regulated by the tidal cycle, as megalopae were more abundant during flood than ebb tides. Although the megalopae do not appear to make large vertical migrations, this behaviour should produce a net shoreward transport. © 2005 Elsevier Ltd. All rights reserved.

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Numerical modeling of the interaction among waves and coastal structures is a challenge due to the many nonlinear phenomena involved, such as, wave propagation, wave transformation with water depth, interaction among incident and reflected waves, run-up / run-down and wave overtopping. Numerical models based on Lagrangian formulation, like SPH (Smoothed Particle Hydrodynamics), allow simulating complex free surface flows. The validation of these numerical models is essential, but comparing numerical results with experimental data is not an easy task. In the present paper, two SPH numerical models, SPHysics LNEC and SPH UNESP, are validated comparing the numerical results of waves interacting with a vertical breakwater, with data obtained in physical model tests made in one of the LNEC's flume. To achieve this validation, the experimental set-up is determined to be compatible with the Characteristics of the numerical models. Therefore, the flume dimensions are exactly the same for numerical and physical model and incident wave characteristics are identical, which allows determining the accuracy of the numerical models, particularly regarding two complex phenomena: wave-breaking and impact loads on the breakwater. It is shown that partial renormalization, i.e. renormalization applied only for particles near the structure, seems to be a promising compromise and an original method that allows simultaneously propagating waves, without diffusion, and modeling accurately the pressure field near the structure.

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The Equatorial Atlantic Margin evolved from three rift systems recorded by a complex set of sedimentary basins developed since Upper Triassic to the Lower Cretaceous (Albian). The first rift system formed Foz do Amazonas Basin in Upper Triassic; the second phase formed Marajó Basin in Berriasian, a new rift in Foz do Amazonas Basin in Valanginian and Bragança-Viseu, Ilha Nova, São Luís e Barreirinhas basins in Aptian; the third phase formed Barreirinhas and Pará- Maranhão basins and a new rifting in the Foz do Amazonas Basin between the Aptian and Albian and evolved to continental break up. The main paleostress field during rift evolution was NE-SW and after the continental break up took the E-W direction, from the development of transform zones in the oceanic crust. From Miocene, South America was subjected to intraplate tectonics, which resulted in formation of E-W transcurrent faults that generated transtensive and transpressive segments that formed sedimentary basins and hills, resulting in changes in the drainage network. In Quaternary the landscape was modified by the last ice age that changed the sea level; the coastal drainage network was drowning resulting in the formation of the current line coast.

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Zircon samples from the Cenozoic São Paulo and Taubaté Basins and Mantiqueira Mountain Range (southeast Brazil) were concomitantly dated by zircon Fission Track Method (FTM) and in situ U-Pb dating method. While FTM detrital-zircon data are ideally used to provide low-temperature information, U-Pb single detrital grain ages record the time of zircon formation in igneous or high grade metamorphic environments. This methodology may be used to study the possible sources of the basins sediments. The results suggest that the São Paulo Basin is composed of sediments from just one source, the Mantiqueira Mountain Range. On the other hand, the Taubaté Basin presents further sediment sources besides the Mantiqueira Mountain Range. © 2012 Elsevier Ltd. All rights reserved.

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The Juréia-Itatins Ecological Station (JIES) is one of the few protected areas in the state of São Paulo, which harbor a significant portion of the Atlantic forest. Although there is high diversity and endemism of fish species in this region, knowledge of the ichthyofauna in JIES is incipient. A total of 4,809 specimens belonging to six orders, 15 families and 31 species were captured during April 2009 to February 2010, using electrofishing, gillnets and traps. The family Characidae was predominant, mainly due to the abundance of freshwater species such as Astyanax ribeirae, Mimagoniates microlepis, and Hollandichthys multifasciatus. Although the estuarine regions were rarely sampled in this study, six brackish water species were captured. In this study, nine species previously unknown from JIES were discovered. Five endangered fish species, endemic to the Atlantic forest, occur at JIES, thus the presence of protected areas, as a conservation measure, is particularly relevant. © 2013 Check List and Authors.

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Water pollution found in major rivers in Brazil has its origin from urban sewage discharges and industrial effluent, carried out by small streams and rivers crossing cities. Therefore, studies related to hydrographic micro-basins offer the opportunity to establish environmental management strategies for restoring water resources, based on diagnosis of the water quality. Despite this understanding, few studies in urban and rural areas have been performed in a systematic manner in Brazilian micro-basins. The main goal of this research was to diagnose the water resources in micro-basins in the region of the district of Americana, São Paulo state, Brazil, through the quantification of metals in water and sediment. The methodology was based on the investigation of metals (Ba, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn), in four micro-basins, determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The most significant result showed high concentration levels of chromium (969 μg L-1), downstream of the discharge of sewage from the city of Nova Odessa. This concentration in the river was above the allowed limit of Brazilian regulation agency (50 μg L-1 for Cr). Also high levels of Cr were found in the sediment (98.9 μg g-1) collected at the same monitored site. These results are important indicators of environmental performance and anthropogenic activities to help the government establish environmental management strategies aimed at the reduction of water pollution. © 2013 WIT Press.

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Pós-graduação em Agronomia (Energia na Agricultura) - FCA

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The Constant Flux: Constant Sedimentation (CF:CS) and Constant Rate of Supply (CRS) of unsupported/excess Pb-210 models have been applied to a Pb-210 data set providing of eighteen sediments profiles sampled at four riverine systems occurring in Brazil, South America: Corumbatai River basin (S1=Site 1, Sao Paulo State), Atibaia River basin (S2=Site 2, Sao Paulo State), Ribeirao dos Bagres basin (S3=Site 3, Sao Paulo State) and Amazon River mouth. (S4=Site 4, Amapa State). These sites were chosen for a comparative evaluation of the performance of the CF:CS and CRS models due to their pronounced differences on the geographical location, geological context, soil composition, biodiversity, climate, rainfall, and water flow regime, among other variable aspects. However, all sediments cores exhibited a common denominator consisting on a database built from the use of the same techniques for acquiring the sediments major chemical composition (SiO2, Al2O3, Na2O, K2O, CaO, MgO, Fe2O3, MnO, P2O5, TiO2 and LOI-Loss on Ignition) and unsupported/excess 210Pb activity data. In terms of sedimentation rates, the performance of the CRS model was better than that of the CF:CS model as it yielded values more compatible with those expected from field evidences. Under the chronological point of view, the CRS model always provided ages within the permitted range of the Pb-210-method in the studied sites, whereas the CF:CS model predicted some values above 150 years. The SiO2 content decreased in accordance with the LOI increase in all cores analyzed and such inverse relationship was also tracked in the SiO2-LOI curves of historical trends. The SiO2-LOI concentration fluctuations in sites S1 and S3 also coincided with some Cu and Cr inputs in the drainage systems. (C) 2014 Elsevier Ltd. All rights reserved.